YAG激光等离子弧复合焊接热源光谱特征分析

利用所研制的YAG激光等离子弧复合热源,进行了不锈钢激光等离子弧复合焊过程的电弧、光致金属蒸气成像观察和光谱分析.研究结果表明,不锈钢的激光焊金属蒸气云与等离子弧具有完全不同的动态特征,其线光谱峰出现在不同的波长带,激光焊Ar谱线波长出现在 520 nm,等离子弧焊的Ar谱线波长均大于696 nm,当激光与等离子弧复合,线光谱是两者的组合,谱线强度增大,可观察到Fe、Cr和Ni等的特征光谱产生.复合焊线光谱特征与激光功率、焊接电流、热源间距和热源顺序密切相关,当热源间距很大时,复合焊的光谱特征实际上是两种热源特征光谱的简单组合,这主要取决于激光与电弧的相互作用.     

Preparation and characterization of silica microcapsules containing butyl-stearate via sol-gel method

For thermal energy storage application in energy-saving building materials, silica microcapsules containing phase change material were prepared using sol-gel method in O/W emulsion system. In the system droplets in microns are formed by emulsifying an organic phase consisting of butyl-stearate as core material. The silica shell was formed via hydrolysis and condensation from tetraethyl silicate with acetate as catalyst. The SEM photographs show the particles possess spherical morphology and core-shell structure. The as-prepared silica microcapsules mainly consist of microsphere in the diameter of 3-7 μm and the median diameter of these microcapsules equals to 5.2μm. The differential scanning calorimetry （DSC） curves indicate that the latent heat and the melting point of microcapsules are 86 J/g and 22.6 ℃, respectively. The results of DSC and TG further testify the microcapsules with core-shell structure.     

机器人焊接技术在钢结构行业的应用

针对钢结构构件的特点及其对机器人焊接的要求,综述了钢结构领域机器人焊接技术的研究现状及发展趋势,指出钢结构构件设计标准化程度低、装配安装精度与机器人智能化程度不匹配是机器人焊接技术在钢结构行业应用的瓶颈问题。通过钢结构构件的模块化、系列化、标准化设计、构建完善的焊接数据库、开发高精度焊缝跟踪技术等方式,逐步提升焊接机器人智能化程度,以攻克钢结构行业机器人焊接技术应用的难题。     

一种新型卷绕方式CPW介绍及应用

主要介绍了德国ＮＥＵＭＡＧ公司开发的新型高速卷统方式ＣＰＷ（致密精密卷绕）的工艺技术特点，并对引进和应用该设备技术的生产情况及其产品质量做了对比分析．     

光学活性物质的工业生产方法

本文介绍了光学８活性牺牲垢几种工业规模的生产方法及最新的进展，分析了各种方法的特点及存在的问题。     

两步法合成双氰胺

本文介绍了采用两步法由石灰氮合成双氰胺的生产工艺，并从浓度、温度、压力、反应时间、酸碱度、生产成本等角度探讨最佳参数，获得符合国家专业标准的双氰胺白色晶体。     

季胺萃取锌的动力学研究

以恒界面池法研究了氯化物介质中季胺萃锌的动力学。考查了搅拌转速、传质界面积和温度对萃取速率的影响，判定季爱萃锌为界面化学反应的动力学模式。进一步研究了季胺萃取剂浓度和水相Ｚｎ＾２＋浓度对萃取速率的影响，得到了与理论推断相吻合的速率方程。     

Oil and fat hydrolysis with lipase fromAspergillus sp.

Hydrolysis of olive oil, soybean oil, mink fat, lard, palm oil, coconut oil, and a hydrogenated, hardened oil with lipase from anAspergillus sp. has been studied. The lipase had high specific activity (60,000 U/g) and did not show any positional specificity. The lipase proved to be a more effective catalyst than Lipolase fromA. oryzae, with an optimal activity at 37°C and pH 6.5–7.0. It was activated by Ca²⁺ but inactivated by organic solvents such as isopropanol and propanone. All substrates examined could be hydrolyzed to corresponding fatty acids with this enzyme at concentrations of 5–30 U/meq with yields of 90–99% in 2–24 h. The degree of hydrolysis was almost logarithmically linear with reaction time and occurred in two stages. The lipase was stable and could be repeatedly recycled for hydrolysis.     

Ti3Al-Nb金属间化合物CO2激光焊工艺

针对高Nb含量的Ti3Al-Nb基合金Ti-23Al-17Nb进行激光焊工艺研究,了解影响钛铝金属间化合物激光焊质量和焊缝成形的工艺因素。研究结果表明,2．5mm厚的Ti-23Al-17Nb合金采用大功率CO2激光焊不产生焊接裂纹,焊缝气孔是主要的焊接缺陷。采用合理的焊前表面处理工艺、全熔透焊接可获得无气孔的焊缝。在所研究条件下,合金具有良好的熔透性,部分熔透和临界熔透时焊缝截面呈钉头型,而稳定的全熔透焊缝则呈“沙漏”形,焊缝熔深并不是完全随焊接热输入的增大而增大,还取决于激光功率密度。接头显微硬度分布呈马鞍形,焊缝的硬度高于母材,近缝区出现峰值,接头的拉伸强度略低于母材。     

建筑配线经济截面的选择方法探讨

低压配电系统的线损在节能方面已成为不可忽视的因素,现行电流密度系数在应用到低压配电系统尤其是建筑配线截面的校验中存在不足,寻求解决室内配线经济截面的方法显得尤为紧迫。通过对确定经济电流密度原理的分析,提出利用最短投资回收期作为确定经济截面的选择方法,并指出利用该方法应注意的一些问题。